Cardiac Embryology Flashcards
When does looping of the heart tube occur?
Week 4
When does the heart tube begin to beat?
e21-22
What provides the precursors for portions of both myocardium and endocardium?
Lateral Splanchnic mesoderm
From where does the splanchnic mesoderm arrise?
-lateral plate mesoderm, forms along with somatic mesoderm
What structures do blood vessels arise from?
Blood islands
What is vasculogenesis?
the process of blood vessels arising from blood islands
What is angiogenesis?
-the process by which new blood vessels sprout from existing ones
What do cells from the first heart field form?
- cardiac crescent
- develops into linear heart tube and left ventricle
What do cells from the second heart field form?
- outflow tracts
- right ventricle
- inflow tracts
What brings the lateral endocardial tubes together in the developing embryo to form a single heart tube?
-Conformational changes due to rapid proliferation of neural tissue and closure of the foregut
What separates the early myocardium and endocardium?
an accelular matrix secreted by the myocardium
What embryonic structure becomes the aortic and pulmonary trunks?
The truncus Anteriosis
What embryonic structure becomes the right ventricle?
The outlet
What embryonic structure becomes the left ventricle?
The inlet
What genes are key in precardiac cell differentiation?
Homeobox genes
What is one of the first manifestiations of embryonic L-R Asymmetry?
-rightward looping of the heart tube
What are basic helix-loop-helix transcription factors?
- bHLH
- are expressed to determine sidedness in the right and left ventricles
Which transcription factor is expressed by the right ventricular segments?
HAND2
Which transcription factor is expressed by the left ventricular segments?
HAND1
What causes the ballooning of the cardiac ventricles?
-disproportionate growth on one side of the heart tube during looping
What are the 4 steps in internal partitioning of the heart tube?
- Atrial septation
- Formation of endocaridal cushions and septation of AV canal
- Ventricular septation
- Septation of the truncus and conus arteriosus
What first divides the atria?
Septum primum
What covers the foramen secundum?
Septum secundum
What forms the flap valve of the foramen ovale?
The overlapping of the septums primum and secundum
When does atrial septation occur?
5 weeks gestation
What does the foramen secundum become?
The interatrial foramen
What does the smooth walled right atrium arise from?
the right sinus horn
What does the smooth walled left atrium arise from?
incorporated common pulmonary vein
What structure becomes the R and L atrial canals?
The common AV canal
What growths form the common AV canal?
endocardial/mesenchymal cushion
What does the first component of the ventricular septum arise from?
folding of the myocardium
Where do the coronary arteries and cardiac veins arise from?
Pro-epicardium
What differentiates/contributes to the SA node?
The sinuatrial ring
What fuses to form the left and right atrioventricular canals?
The superior and inferior endocardial cushions
What serves as an anchoring point for atrial and ventricular septa and AV valves?
The fused endocardial cushions
How are the AV valves formed?
- Myocardium covered by cushion is “undermined”
- Myocardium retracts and is replaced by dense connective tissue
- Myocardium remaining nearer the apex forms the papillary muscle
What forms the aortico-pulmonary septum?
Fusion of the endocardial ridges
What is the aortico-pulmonary septum?
-divids the conus and truncus into an aortic and pulmonary channel
What special cells contribute to endocardial cushion formation is the truncus arteriosus and conus cordis?
-Neural crest cells
What forms the link between cardiac and craniofacial abnormalities?
-The abnormal migration, proliferation, or differentiation of neural crest cells
What shunts oxygenated blood from the umbilical vein to bypass the liver?
Ductus venosus
What results in pulmonary overcirculation?
- Ventricular septal defect
- Oxygenated blood from left ventricle is being pumped through the septum into the pulmonary circulation
What is Tetralogy of Fallot?
- Tetralogy = 4 anomolies:
- pulmonary stenosis
- VS defect
- Aortic override
- Right ventricular hypertrophy
What results in pulmonary stenosis and Aortic override?
The malalignment of the conoventricular septum
What results in the ventricular septal defect in the tetralogy of fallot?
-The malalignment of the conoventricular septum causes it to not align with the interventricular ridge
What results in the right ventricular hypertrophy in tetralogy of fallot?
-The stenosis of the pulmonary trunk causes the right ventricle to work harder, and get bigger
What is aortic override?
- The aorta is positioned right over an ventricular septal defect, instead of in the left ventricle
- happens in tetralogy of fallot
What are the symptoms of tetralogy of fallot?
- decreased pulmonary blood flow
- Desaturation at rest
- progressive cyanosis without repair
- “Blue” spells
What happens to the ductus arteriosus in patients with tetralogy of fallot?
- It remains patent
- blood flows from aorta, through ductus arteriosus, and into the pulmonary arteries
- closes later on
What is it called when the heart folds to the right instead of left?
Dextrocardia
